Treatment of textile fibers



Dec. 20, 1960 s. ROBINSON 2,964,803

TREATMENT OF TEXTILE FIBRES Filed July 18, 1957 3 Sheets-Sheet 1 J lnuentqr $3AQRJWM. I.

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Dec. 20, 1960 s. ROBINSON 2,964,803

TREATMENT OF TEXTILE FIBRES Filed July-18, 1957 3 Sheets-Sheet 2 S im Robinson Inventor m d A ftorney;

Dec. 20, 1960 s. Rosmscm 2,964,803

TREATMENT OF TEXTILE FIBRE'S Filed July 18, 1957 3 Sheets-Sheet s i a l I j 52+ 35 L 1 I AMPLIFIER IZLI UL, E

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United States Patent TREATMENT OF TEXTILE FIBRES Sydney Robinson, Ilkley, England, assignor to Stanley Whitaker Jackson, Yorkshire, England Filed July 18, 1957, Ser. No. 672,691

Claims priority, application Great Britain July 18, .1956

11 Claims. (Cl. 19-70) The treatment of many kinds of textile fibres includes the process known as drafting by which the. thick ness of a rope or strand of fibres is reduced and its length increased.

Although drafting may be effected in many ways the process in one form or another usually consists in passing the textile strand, for example a sliver, between two pairs of rollers arranged in succession along the strand and driven at different speeds so that the part of the, strand which extends between the pairs of rollers is stretched. The difference in speed at which the pairs of rollers are driven will determine the drnting ratio and this ratio will be selected according to tne nature of the treatment required. It is of course of the utmost importance that the resultant product shall be even and of a standard weight per unit length. However, if the strand or sliver fed to the drafting machine varies greatly in quality or size it will be difficult to ensure an even product and in conventional textile processes many stages of drafting and doubling may be required.

In the case of wool fibre, for example, it' is most important, in order that a uniform sliver is obtained, that the fibres shall be thoroughly intermixed and this presents difficulties since the tops in even the same combing are never absolutely uniform in content and the divergence is even more obvious when blending different makes or qualities of tops. It is very important that a uniform fibre distribution should be obtained in the early stages of drawing since a lack of uniformity in the sliver can never be cured subsequently and will manifest itself as thick and thin places in the roving or as. irregularities in the yarn.

The above difficulties apply equally to other textile fibres and also when making colour blends or mixtures where success depends on the intimate distribution of each colour or material in the final roving.

It has accordingly been proposed to vary by.mechanical means the relative speed of the drafting rollers in accordance with departures from standard of the thickness or diameter of the sliver as it isfed to thefmachine so that a compensating action may be efiected during the drafting process. Such mechanical arrangements are, however, complicated, and difficult to apply to existing machines, and they are incapable ofa precise control of the drafting operation.

It is an object of the present invention to, provide an improved arrangement for controlling the drafting operation in such. a manner as to provide a substantially uniform product. A further object is. to provide an arrangement of this kind which can beapplied to ex'sting text le machinery with a minimum of structural modification.

arrangement in which the drafting of a textile sliver is 2,964,803 Patented Dec. 20, 196;;

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controlled by electric signals representative of the instantaneous thickness or weight of the sliver as it approaches the drafting machine, the said signals being applied to control the operaton of the machine in such manner as to compensate for variations in thickness or weight of the sliver. i

Other objects and novel features of the invention will become apparent during the course of the following description with reference to the drawings in which:

Figure 1 is a diagrammatic side elevation of a typical intersecting gill box, I

Figure 2 is a diagrammatic representation of a .gill box arranged for operation in accordance with this invention,

Figure 3 is a diagrammatic view of a device for detecting changes in weight or thickness of a textile sliver,

Figure 4 is a diagrammatic illustration of a signal storage device,

Figure 5 shows part of the electronic control apparatus used in the arrangement of Figure 2, and

Figures 6, 7 and 8 show alternative variable speed arrangements.

In its simplest form the invention may be applied simply to control a drafting operation and in such case would operate to control the speed of one pair of rollers relative to the speed of the other pair of rollers. However, in most textile machines the operation of a eaing is combined with other operations and in order that the invention and its application may be clearly understood it will now be descr.bed as applied to the control of a normal intersecting type gill box.

A machine of this kind is shown diagrammatically in Figure 1' and comprises a pair of spring-loaded fluted rollers 1, the back rollers, which feed one or more slivers 2 into the machine where they are operated on by the pins of fallers 3. The fallers are moved in the direction of movement of the sliver and their pins pierce the sliver and carry the fibres towards the front end of the machine where another pair of fluted rollers 4 grasp the fibres and draw them away from the. faller pins. The material emerges as a thin sheet which is again condensed into a sliver by press rollers 5 and fed into a sliver can 6. In the operation of the machine the front rollers 4 are driven at a speed which is greater than that of the back rollers 1 and 'this difference in speed determines the amount of drafting which occurs, In all normal machines of thiskind both pairs of rollers are driven through gearing from a prime mover but change wheels are providedby which the draft ratio can be changed to suit the required duty of the machine Such a change in speed is usually applied to vary the speed of the back rollers 1 and the fallers 3v relative to the speed of the front rollers 4 which latter may be kept constant.

The drafting may be considered to occur at some point in the faller bed such as is indicated by the. arrow Y which will varyin position according to the average length of the fibres being drafted but which for a given yarn can be located and will remain reasonably constant for this yarn. However it will be seen that if an attempt is made to vary'the drafting ratio to take into account variations in thickness of the sliver reaching the machine, the measurement of the sliver can only be effected at some point in front of the machine as indicated by the arrow Accordingly any correction applied to the speed of the back rollers 1 must be delayed until the point on the sliver measured at X reaches the drafting point Y and it will be appreciated that the delay time required must be connections being shown in full lines and electrical connections in dotted lines. The gill box is represented by a pair of rollers 4 which are the front rollers, a pair of rollers 1 which are the back rollers, and by the faller bars 3 and their drive 7 which is taken from the drive to the back rollers 1 as indicated. The front rollers 4 are driven through gearing 8 from a prime mover 9 while the back rollers and taller bars are driven from the prime mover 9 through a variable speed device 10. It may be observed here that the normal gill box is arranged as above described except that a constant speed drive is used instead of the device 10, the gear ratio of the constant speed drive being changeable as by the substitution of gear wheels to suit conditions of operation.

The arrangement of the present invention includes in addition to the variable speed gear 10 the following apparatus:

(l) Detecting means 11 for producing an electric signal corresponding to the thickness or weight of the sliver 2 as it reaches the machine;

(2) Means 12 for storing the signals and delivering them after a controlled interval of time, and

(3) Electronic means 13 responsive to the delayed signals for controlling the operation of the variable speed device 10.

The detecting means 11 is designed to measure the thickness or weight of the sliver at a point in its length before it reaches the back rollers 1 of the gill box and to provide an electric signal proportion l to such thickness or weight. Anv suitable means for th s purpose may be used. A simple but effective arrangement is shown diagrammatically in Figure 3 and comprises a fl nged pulley 14 over which the sliver is passed and a roller 15 which fits between the flanges of the pulley 14 and is held against the pullev by a constant force. In this manner the sliver is compressed into a space of uniform width and the s acing of the roller 15 from the pulley 14 will determine the thickness of the sliver and hence its weight per unit length. The roller 15 may be mounted, as shown, on one end of a lever 16 which is pivoted intermediate its ends at 17 and from which a wei ht 18 is hung so as to hold the roller 15 against the face of the pulley 14. The lever 16 is also connected with a rack 19 which acts on a gear wheel 20 effective. when the lever 16 moves, to move a sliding contact 21 over an electrical resistance 22 which is connected across a source of constant potential whereby an electric signal may be obtained at terminal 23 which is proportional to movement of the roller 15 and hence the thickness of the sliver 2.

Alternatively the quantity of material at the measuring point may be measured by exposing the material to emission from a radio active source and measuring the intensity of radiation which passes through the material.

The electric signals roportional to the weight or thickness of the sliver and however obtained have to be applied to produce a compensating elfect in the drafting process. However. the measurement of the weight or thickness of the sliver must necessarilv be effected at some point behind the back rollers while the point at which the drafting efiect takes place lies somewhere between the front and b ck rollers at a position which is variable according to the quality of the sliver. Accordinglv even if the sliver moves at constant speed there is a definite interval for the pass e of any point on the sliver from the detector to the dr fting point. It is accordingly necessary to provide a delay in the operation of the variable speed device 10 consequent on the detection of a change in thickness of the sliver and this delay must be adjustable to allow for variation in position of the drafting point. Moreover additional means must be provided to compensate for changes in the speed of movement of the sliver.

The arrangement of the present invention therefore provides means 12 for storing the signal f Q l 1 6 fi fi 4 tor 11 which are driven at a speed proportional to the speed of rotation of the back rollers 1 and which are capable of delivering the stored signals after a delay which may be adjusted.

This storage system comprises a plurality of condensers which are connected synchronously with the movement of the back rollers so as to sample the output from the detecting means 11 at timed intervals which may represent, for example, one inch of travel of the sliver, the condensers charged by the signals from the detecting means being subsequently synchronously connected with the electronic control means 13.

In one suitable arrangement diagrammatically shown in Figure 4 one terminal of each of a plurality of condensers 24 is connected with a corresponding segment of a commutator 25 while the other terminals are connected in common. The commutator and two brushes 26, 27 operating thereon are arranged to be relatively rotatable at a speed proportional to the speed of the back rollers. The brush 26 is connected with the output from the detecting means 11 so as to charge each condenser 24 in succession and the other brush 27, which is angularly adjustable relative to the first to provide adjustment of the delay time, collects the charge on each condenser in succession and applies it to the control apparatus. The second brush 27 may be followed by a third brush 28 which acts to remove all charges from each condenser so that they are ready to be charged by the first brush 26.

In the arrangement illustrated it is contemplated that the commutator 25 is fixed and that the brushes 26, 27 and 28 are rotated, connections to the brushes being made in conventional manner by means of the slip-rings shown. In an equivalent arrangement the condensers 24 may each be connected between respective segments of two commutators and the whole rotated relative to a fixed set of brushes acting on each commutator.

In order to produce variation in the speed of the back rollers 1 in accordance with changes in the signal from the detecting means 11, the delayed signals are applied to the electronic control means 13 (Figure 2) which in turn operates to control the speed ratio of the variable speed device 10 in a manner to be described below.

Figure 5 illustrates diagrammatically the electrical connections of the detecting means 11, the signal storing means 12, and the electronic control means 13 which in one form of the invention operate to control the speed of a servo motor. As shown, the resistor 22 of the detecting means 11 is connected between ground and a source of potential through an adjustable resistor 30 which enables the mean value of the signal level to be controlled. The moving contact 21 of the detecting means 11 is connected with the brush 26 of the signal storing means 12, the mechanical arrangement of which is as described with reference to Figure 4, while the brush 27 is connected with the control grid of cathode follower tube 31 whereby a potential is applied to this tube which is substantially the same as that on the sliding contact 21 but delayed by a time interval which is a function of the separation of the brushes 26 and 27 and the relative speed of rotation of the brushes and condenser assembly. The potential at the cathode of tube 31 is applied to the input terminal of an amplifier 29 which is a DC. amplifier of conventional construction and need not be described in detail and which controls the current in the field winding 32 of the servo motor 33. The armature of this motor is energized from a suitable constant current source and is mechanically coupled with the armature 34 of a DC. tachometer generator 35, the output of which is proportional to its speed of rotation, so that the two devices are rotated at the same speed. The output from the tachometer generator 35 is also applied to the input terminal of amplifier 29 but in opposition to the signal derived from the detecting means 11. In such an arrangement and with the servo motor 33 operating at a definite speed, the sigpals from the tachometer generator 35 and the ,detect ing means 11 being equal, if the thickness of the silver changes the signal from the detecting means 11 will change and the speed of the servo motor 33 will change until the signal from the tachometer generator 35 is again equal to the new level of the signal from the detecting means. In this manner the speed of the servo motor 33 will be held proportional to the thickness of the silver. The use of the tachometer generator 35 as described provides a feedback circuit which enables a sensitive control of the speed of the servo motor 33 to be obtained and operates to prevent hunting.

The servo motor may be arranged to control the variable speed device and hence the speed of the back rollers 1 in various ways.

In the arrangement shown in Figure 6, the variable speed device consists of a differential gear 37 of conventional construction. The servo motor 33 is connected to drive one member of the gear 37 by the shaft 38 and another member of the gear is driven at constant speed by the prime mover 9 (Figure 2) through a chain drive and shaft 39. The third member of the gear is connected by, a shaft 40 and a chain drive to drive the back rollers 1 and the speed of revolution of shaft 40 will be proportional to the speed of revolution of the servo motor 33. While this arrangement is practicable any variation in load on the back rollers 1 will be transmitted back into the servo motor 33 which must accordingly provide appreciable power and hence may have an inertia which is too high to permit a fine control of speed.

An alternative arrangement which avoids this difficulty is shown in Figure 7. In this case use is made of a variable speed gear 41 of known kind which provides a smooth change in ratio on the movement of a control lever. This gear is connected with the prime mover 9 by a chain drive and shaft 42 and with the drive to the back rollers by shaft 43. Its operation is controlled by the servo motor 33 through a differential gear 44 one member of which is driven by the motor and another is driven from the output side of the variable speed gear 41 by a chain drive from shaft 43, and accordingly at a speed proportional to the speed of the back rollers. If the two members rotate at the same speed the third member would be stationary. This third member may thus be connected with the control lever of the variable speed device 41 by means of a crank 45 and link 46. Accordingly any change in speed of the servo motor 33 would produce a movement of the third member of the differential gear 44 which operates to vary the speed ratio of the variable speed gear 41. Accordingly the speed of the back rollers will be changed and simultaneously the speed of the second member of the differential would be changed in proportion. This change will continue until the first and second members of the differential again run at the same speed when the third member will again be stationary at a new setting.

The arrangement is a mechanical equivalent of the servo motor tachometer generator arrangement described above and provides a feedback system which is self balancing and which makes the arrangement stable and free from hunting and overshoot.

The arrangement also has the advantage that changes in load on the back rollers are not transmitted to the servo motor. It is accordingly possible to use a small and light motor with improved speed sensitivity.

In a further arrangement illustrated in Figure 8 the variable speed device consists of an eddy current coupling, for example of the kind known as a Heenan-Dynamatic coupling. Such a device comprises two members, one connected to a driving shaft and the other connected to a driven shaft, which are separated by an air gap and which are coupled only by eddy current mag- :netic :drag. In such an arrangement the speed of "the driven member maybe varied between substantially zero and the speed of the driving member by control of direct current in an exciting coil carried on one of the members. Such a device is shown at 47 in Figure 8, the driving shaft 48 being coupled by a chain drive to the prime mover 9 (Figure 2) and the driven shaft 49 being coupled by a chain drive to the back rollers 1 (Figure 2). A tachometer generator 50 is also coupled to the driven shaft and supplies a signal proportional to its speed of rotation to electronic control gear 51 in opposition to a signal obtained from the cathode follower 31 of Figure 5. The tachometer generator 50 controls the operation of the coupling in so far as small variations of speed are concerned and it is otherwise responsive to the signals obtained from the cathode follower which represents the thickness of the sliver. The electronic control gear 51 is responsive to the signals from the tachometer generator 50 and the cathode follower 31 to control the current in the exciting coil of the coupling and thereby to vary the speed ratio in accordance with change in either of these signals.

It will be appreciated that other forms of variable speed device may be used the important thing being that such device is able to vary the speed of the back rollers in accordance with departures from standard of the weight of the sliver.

In using the arrangement of this invention more than one sliver may be fed to the gill box. All such slivers may be fed over the flanged roller 14 (Figure 3) so that their combined thickness is measured. Alternatively the thickness of each sliver may be measured separately and the signals from the several detectors combined to give a resultant signal representing the total thickness. This may enable a more sensitive measurement of the total thickness to be obtained and suitable warning means could be provided to indicate whether any of the slivers was broken or missing although the automatic control would nevertheless be able to apply compensation for the omission of one out of, say, five slivers.

The arrangement of the present invention is capable of compensating for considerable variations in the incoming sliver and in one case a range of 15% in weight of the sliver has been successfully handled and a level output sliver produced.

The application of the system of this invention to existing textile machinery is very simple since, for example, in the case of a gill box it is only necessary to disconnect the drive between the front and back rollers and to connect the shaft ends, for example, by a chain drive with the differential gear 37 of Figure 6 or the variable speed gear 41 of Figure 7 or 47 of Figure 8 which, with the servo motor 33 if used and the associated electronic equipment, may be housed in any convenient position. Apart from this it is only necessary to arrange the detectors adjacent the machine where they can engage the incoming sliver.

The automatic compensating means of this invention may be applied to many types of textile machinery and its use is not limited to gill boxes of the intersecting type, for example it may also be successfully used in draw boxes, or merely to control a drafting operation.

What I claim is:

1. Apparatus for controlling the operation of drafting mechanism for textile slivers comprising detecting means for producing electric signals representative of variations in weight of said sliver as it approaches said mechanism, electromechanical means for storing said signals for a controlled period of time, and means responsive to said stored signals for varying the speed of operation of said mechanism in accordance with said variations in weight, said electromechanical means comprising a plurality of electric condensers which are connected individually in succession to be charged by said signals and to deliver the stored signals to said speed varying means.

2. Apparatus as claimed in claim 1, in which said speed varying means includes a servo motor, means for controlling the speed of operation of said servo motor in accordance with the magnitude of said stored signals, and a variable speed device controlled by said servo motor.

3. Apparatus as claimed in claim 2, in which said variable speed device is a differential gear having a first member adapted to be driven by a prime mover, a second member driven by said servo motor, and a third member adapted to drive said mechanism.

4. Apparatus as claimed in claim 2, in which said variable speed device comprises a gear box having a continuously variable gear ratio and control means for adjusting said gear ratio, and a differential gear having a first member coupled with the driven shaft of said gear box, a second member coupled with said servo motor, and a third member coupled with said gear ratio control means.

5. Apparatus as claimed in claim 1, in which the means for varying the speed of operation of said mechanism includes an eddy current coupling adapted to be driven by a prime mover and to drive said mechanism, said coupling including an exciting Winding the current in which is controlled in accordance with the magnitude of said stored signals.

6. Apparatus for controlling the operation of drafting mechanism for textile slivers comprising detecting means for producing electric signals representative of variations in weight of a sliver approaching said mechanism, signal storing means for delaying said signals for a controlled period of time, said storing means including a plurality of electric condensers adapted to be connected in sequence to be charged by said signals and to discharge into a load circuit, a variable speed device connecting said mechanism with a prime mover and com prising an eddy current coupling including an exciting winding and electronic control means for varying the current in said exciting winding in proportion with the potential set up in said load circuit.

7. Apparatus as claimed in claim 6, in which the connection of said condensers is effected by a commutator switch which is rotatable relative to cooperating brushes at a speed proportional to the speed of said mechanism.

8. Apparatus as claimed in claim 6, including a tachometer generator coupled with the driven member of said coupling and providing a signal which is opposed to said delayed signals.

9. Drafting mechanism for controlling the thickness of a travelling textile sliver comprising a first and a second pair of rollers engaging said sliver at spaced points thereon, said first pair of rollers engaging said sliver in advance of said second pair of rollers, means for detecting changes in thickness of said sliver as it approaches said first pair of rollers and for producing electric signals proportional to such variations in thickness, means coupled with said first pair of rollers for storing said signals for a predetermined interval of time, said signal storing means including a plurality of electric condensers adapted to be charged in succession by said electric signals, a variable speed coupling means connecting said first pair of rollers with said second pair of rollers, said second pair of rollers being adapted to be driven at constant speed, and means for controlling the operation of said variable speed means in response to changes in the magnitude of said stored signals.

10. In drafting mechanism for controlling the thickness of a travelling sliver and including means for producing electric signals representative of variations in thickness of said sliver as it approaches the mechanism and means for controlling the speed of operation of part of said mechanism in accordance with the magnitude of said signals, signal storing means for receiving said signals and for storing them for a predetermined interval of time, said signal storing means including a plurality of electric condensers arranged for connection in sequence with said signal producing means at a speed pro portional to the speed of operation of the said part of said mechanism.

11. Signal storing means as claimed in claim 10 including a commutator switch coupled with the said part of said mechanism, an input and an output brush on said commutator, said brushes being movable relative to each other for varying their angular position.

References Cited in the file of this patent UNITED STATES PATENTS 2,518,405 Van Duuren Aug. 9, 1950 2,810,936 Altenburger Oct. 29, 1957 2,812,553 Coulliette Nov. 12, 1957 FOREIGN PATENTS 900,669 Germany Dec. 28, 1953 

